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United States Patent O?lice 3,077,104 Patented Feb. 12, 1963 it 2 serves as a quantitative marker for the interface or mix 3,677,1ii4 PRGCESS FUR DETECTING THE ENTERFACE BETWEEN TWO ABJAQENT FLUED§ Frank C. Fowler, 1451B). 76th Terrace, Kansas City 10, M0. N0 Drawing. Fiied May 27, 1959, Ser. No. 816,653 3 (Claims. (Ci. ‘73-53) ture separating two adjacent ?uids. In another aspect of this invention, the halogenated hydrocarbon is admixed with the fluid to be transported through the conduit. If any leaks are present in the con duit for transporting the ?uid, portable detecting equip ment is passed along the conduit to detect the presence of the halogenated hydrocarbon. Very minute quantities of The present invention relates to a novel and useful the halogenated hydrocarbon can be detected thereby in method of detection of the presence of materials and to a 10 dicating the presence of a leak in the conduit. composition used therefor. In one aspect my invention The halogenated hydrocarbon used as the detecting relates to a method for detecting the interface between medium may be partially or completely halogenated; and two adjacent ?uids when ?owing successively through a preferably, the halogens are selected from the group con conduit. In another aspect this invention relates to a sisting of ?uorine and chlorine. The halogenated hydro method for detecting leaks of ?uids from con?ned areas. 15 carbon should be miscible with the ?uids to be trans There has been an increasing demand for a method of ported when in the liquid phase. That is, the halogenated accurately detecting and measuring the interface separat ing adjacent products in a product pipeline. The several methods in use can be classi?ed into two groups. One hydrocarbon should be soluble in the liquid ?uid to be transported in the amounts necessary for proper detection. Preferably, the halogenated hydrocarbon is normally gase group involves those measuring a property of the product 20 ous material. Suitable examples of halogenated hydro being transported, such as density, ?ash point or dielectric carbon are those containing ?uorine or chlorine or both, constant. The other group measures a property of a having not more than three carbon atoms per molecule. tracer or marker which is injected into the line at the inter However, halogenated hydrocarbon of longer chain length face. The marker may be a dye or a radioactive tracer. may be used Without departing from the scope of this in The di?iculty with measuring a property of the prod 25 vention. Typical examples of the halogenated hydro ucts is that occasionally products with nearly identical carbon include dichlorodi?uoromethane, dichloromono properties are adjacent to each other in the pipeline. For ?uoromethane, trichloromono?uoromethane, trichlorotri instance, it is possible for two gasolines to have almost ?uoroethane, and dichlorotetra?uoroethane. Since for the identical densities or dielectric constants. This situation best detection process it is desirable that the halogenated produces such little change in the measured quantity that hydrocarbon be in the vapor phase, the above compounds an interface cannot be detected. Rarely will large ship, are particularly useful since they are normally gaseous. ments of products be characterized by exactly the same However, any halogenated hydrocarbon which is volatiliz density or dielectric constant because uniform mixing able is usable, such as chloroform, carbon tetrachloride, throughout large storage tanks does not exist. Thus, mis and tetrachloroethylene, which are normally liquid but leading indications of the presence of an interface can 35 volatilizable. Mixtures of the halogenated hydrocarbon occur because of inability to insure complete homogeneity ‘ may be used without departing from the scope of this in within the storage tanks and transfer lines. vention. Such mixtures are particularly desirable to pro The use of a dye as a marker which depends upon visual vide a vapor pressure of the detecting medium correspond or colorimetric measurements has certain disadvantages. ing substantially to‘ the vapor pressure of the fluid to be Certain products, particularly crude oil, possess color 40 transported. ' A particularly desirable mixture is a mix which interferes with visual observations. Measurement of color with colorimetric equipment requires expensive apparatus, costly to install and maintain under ?eld con ditions. Radioactive tracers present the problem of ade quate safety measures to insure the safety of operators. An object of this invention is to provide a method for detecting the presence of ?uids. Another object of this invention is to provide a method for detecting different ?uids while ?owing in a conduit. 50 Still another object of this invention is to‘provide a method for detecting leaks of ?uids from con?ned areas. Still another object of this invention is to provide de tecting medium which is miscible and inert with the ?uids to be detected. Still another object of this invention is to provide a detecting medium which is more sensitive and more eco nomical than present media used for detecting the pres ence of ?uids. ture of dichlorodi?uoromethane and dichlorotetra?uoro ethane in equal molar proportions when used as a detecf tion medium for transporting hydrocarbon. The detection medium should be present in an amount at least 0.1 p.p.n1., and preferably, an amount between about 25 and about 500 ppm. In these proportions the halogenated hydrocarbon is usually miscible with most organic ?uids. In most instances, it is unnecessary to use much more than 100-150 ppm. of the halogenated hy drocarbon for detection purposes. In the case of detect ing leaks in conduits in which the ?uid is being held, as small as 1-10 ppm. of the halogenated hydrocarbon is all that is required. ' The present invention is particularly useful in trans porting hydrocarbons, particualriy in the transportation of petroleum oils and distillates. ‘For example, the pres ent invention applies to transporting crude oil, gasolines, kerosenes, diesel oil,‘ fuel oil and various petroleum dis Various other objects and advantages will become ap 60 tillates. The invention also is applicable to the trans portation of other organic chemicals, such as alcohol, parent to those skilled in the art from the accompanying description and disclosure. According to the present invention, a halogenated hy drocarbon is injected into the final portion of the leading ethylene, propane and ethylene glycol. The invention applies particularly to the transporta tion of various petroleum liquids and fractions. For the interface is detected. The halogenated hydrocarbon present invention, therefore, is an economical and sensi example, in the transportation of crude oil it is necessary ?uid or the initial portion of the flowing ?uid in a conduit 65 often to detect the difference between crude oil supplied in which the ?uids are ?owing successively through said by different suppliers or to indicate the crude oil to differ conduit. Equipment capable of detecting the halogenated ent customers. In addition, different products in quality hydrocarbon is located downstream from the point of in and grade may be transported through the same conduit, jection. As the interface containing the halogenated hy 70 but their physical and chemical properties are so closely drocarbon passes the detecting equipment, the presence of similar that it is di?icult to detect the interface. The 3,077,104 3 4 tive method for detecting the interface between similar petroleum products, such as two different gasolines or gasoline and kerosene, etc. In this respect, in transport The detecting equipment would function by diverting had been marked, then the Freon concentrations would gradually rise to the concentration at which it was in jected. In this example, the value would be 100 p.p.m. As the interface passed the measuring station, the Freon concentration would decrease again, reaching zero when all of the mixture had passed. Similar results are also obtained by injection of the Freon into the ?rst portion of gasoline B. Still another method involves injection of a small stream as a vapor from the conduit or pipeline a concentrated quantity of Freon at the interface for a ing gasolines the halogenated hydrocarbon mentioned above is inert‘ and has no effect upon the anti-knock prop erties of the gasoline when used in the proportions set forth above. to the measuring element. One typical method of detect 10 shorter time. Detection elements located downstream would give a zero reading followed by a rapidly increas ing halogenated hydrocarbons, such as the ?uorine-con ing reading to a maximum value. The value would then taining Freons, is based upon the principle that a heated decrease rapidly to Zero again. platinum surface emits substantially larger numbers of A Freon ?ag would not be affected by contamination ions in the presence of halogen gases. Suitable equip ment of this nature is available on the open market and 15 from line-?lls, line-traps or leaking valves. This factor gives erroneous results when using the physical property one such equipment is sold by the General Electric Com of the products as a means of identi?cation. pany as G.E.-C233G leak detector used for detecting Besides identifying the interface, the use of Freon ?ags Freons. Another useful method is to take advantage of offers a very sensitive method of detecting small leaks the green color imparted to the burning ?ame of hydro carbons by the presence of halogen. Thus, a small sam~ 20 from the pipeline. Concentrations of less than 1 p.p.m. Freon in air may be easily detected. The use of the more ple of a ?owing hydrocarbon in the conduit may be volatile Freons increases the concentration of Freon in burned to indicate the presence of halogens. air resulting from a pipeline leak. Several methods may be used for converting the liquid As a speci?c example of the operation of this invention stream in the conduit to vapor to be passed through the detecting equipment. Among these are: 25 in the transportation of two different batches of gasolines through a 100 mile long 8 inch pipeline at the source of supply, 100 p.p.m. of Freon~12 is injected into 300 barrels of the ?rst batch of gasoline at the end of the supply of such gasoline and before the supply of the (4) Combustion of liquid with measurement on the ?ue 30 second batch of gasoline. This corresponds to about one gases mile of injection in the pipeline. At the end of the Any of the above methods may be used to produce the 100 mile pipeline more than 300 barrels of gasoline will desired results. Sensitivity, safety and economy dictate be marked by the Freon due to diffusion. The detection their choice. equipment will ?rst indicate 0 p.p.m. of the Freon and The Freons as the detecting media offer a wide range gradually indicate higher quantities until it reaches about 35 of boiling points which, in turn, permit a wide choice of 100 p.p.m. This will allow sufficient time for the oper methods for injection and detection. Choice of different ator to be ready to mark the change in the interface. Freons allows variation of the sensitivity required in de Then, when the detection equipment starts to indicate a tection. The most urgent need for better methods of decreasing Freon concentration, the operator will know detection is in product pipelines, where the principal prod that the interface has arrived. ucts to be transported are gasoline and light distillates. Various modi?cations and alterations of the quantity The use of Freons as a detecting media is adaptable to a and means of detection may become obvious to those wide variation of petroleum products from methane skilled in the art without departing from the scope of through crude oil. As a matter of fact, of the current this invention. methods in use, none seems well suited to the identi?ca Having described my invention, I claim: tion of crude oil interfaces. Freons can be used quite 45 1. A method for detecting the interface between two satisfactorily in crude oil lines. Increasing use of pipe adjacent batches of gasoline successively ?owing through lines for shipment of chemicals is being made. The a conduit which comprises injecting a miscible ?uorinated Freons will perform well in most applications of chemi hydrocarbon adjacent to said interface in an amount cal shipments. Freons or halogenated hydrocarbons offer some impor 50 between about 0.1 and about 500 p.p.m. of the gasoline and subsequently downstream from the point of injection tant advantages when used as markers. First of all, they removing a portion of the gasoline containing said ?uori 'are completely miscible with hydrocarbons and many nated hydrocarbon, vaporizing said portion of the gasoline other chemicals in the ranges under consideration. Spe thus removed and determining the presence of ?uorinated ci?cally in the transportation of petroleum products by pipelines, small quantities used in this invention do not 55 hydrocarbon in said gasoline. 2. The process of claim 1 in which said ?uorinated affect the speci?cations or the use of the products. Many hydrocarbon is a mixture of dichlorodi?uoromethane and of the Freons possess the added advantage of being non dichlorotetra?uoroethane. toxic and non?amma-ble. 3. A method for detecting the interface between two A Freon or a mixture of Freons selected for a‘ given identi?cation would be injected at a speci?c rate, depend 60 adjacent batches of hydrocarbons successively ?owing through a conduit which comprises injecting a miscible ing upon the concentrations desired in one of the two ?uorinated hydrocarbon adjacent to said interface in adjacent products. For instance, Freon-12 could be in an amount between about 0.1 and about 500 p.p.m. of jected into the gasoline at the rate such that the concen the hydrocarbon and subsequently downstream from the tration would be 100 p.p.m. Freon-12 in the gasoline. This would be done in one of the two adjacent gasolines 65 point of injection removing a portion of the hydrocarbon (1) vaporization by application of heat (2) Flashing by reduction in pressure (3) Stripping by inert gas such as nitrogen being pumped through pipelines. If gasoline A were being pumped into a pipeline followed by gasoline B, then the interface between the two gasolines would be a mix ture of A and B. Consider that the Freon were injected in the last portion of the gasoline A as it was being pumped 70 into the pipeline. The measuring instrument, located at the next station, would indicate zero p.p.m. Freon at ?rst. Then the measuring element would detect increasing amounts of Freon in gasoline A as the interface ap proached that station. It su?icient quantity of gasoline 75 containing said ?uorinated hydrocarbon, vaporizing said portion of the hydrocarbon thus removed and determin ing the presence of ?uorinated hydrocarbon in said hydro carbon. References Cited in the ?le of this patent UNITED STATES PATENTS 1,090,737 McDonald __________ __ Mar. 17, 1914 (Other references on following page) 5 3,077,104 UNITED STATES PATENTS 1,693,737 Weldon _____________ __ Dec. 4, 1928 2,631,242 2,631,929 Metcaif ____________ __ Mar. 10, 1953 2,775,120 Thorpe et a1. _______ __ Mar. 17, 1953 Bennett ct a1. ________ _.. Dec. 25, 1956 6 2,784,160 2,868,625 Blaker ______________ __ Mar. 5, 1957 Frank ______________ __ Jan. 13, 1959 OTHER REFERENCES General Electric Review. October 1949, pages 41-44, article by J. R. Ne?.